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| Format: | Artículo científico |
| Language: | en |
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Universidad Nacional Autónoma de México
2003
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| Online Access: | https://www.redalyc.org/articulo.oa?id=56842325 |
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Table of Contents:
- Short-term climatic change in lake sediments from lake Alchichica, Oriental, Mexico Alejandro Rodríguez Diana Juárez Margarita Caballero Gloria Vilaclara Ciencias de la Tierra diatoms Maar lakes Oriental Basin Reduced precipitation in central Mexico is related to ENSO events. These short-term climatic fluctuations can modifymixing-stratification patterns of lake systems, reflected in the sediments deposited at the bottom year after year. Lake sedimentscan also record longer climatic trends. We present preliminary results of an evaluation of the potential of Lake Alchichica to recordshort-term fluctuations as well as middle-term climatic variability. Diatom, loss on ignition (LOI) and total pigment analyses werecarried out on a 168 cm core from the NE shore of Alchichica. Two 14-C dates on bulk sediment give an approximate chronologicalframe for the sequence. Total pigment content was a poor palaeoenvironmental proxy in this lake, as pigments were undetectedbelow 56 cm, suggesting that concentration depends on degradation processes. Diatom preservation in the sediments was poor andrestricted to the upper 44 cm. High pH and alkalinity in Alchichica favor diatom dissolution, limiting the potential of this lake forpalaeolimnologic studies. Diatom assemblages in the upper 44 cm of the sequence suggest that the lake has remained an alkalinesubsalinesystem during the recent past, probably over the past 300 yr., with a very recent decrease of lake level. There is no recordof short-term climatic events such as ENSO. Sediment stratigraphy and LOI data, however, suggest a past event of unknown age(>300 yr. ?), with lower than present lake levels and higher alkalinity. 2003 artículo científico 0016-7169 https://www.redalyc.org/articulo.oa?id=56842325 en http://www.redalyc.org/revista.oa?id=568 Geofísica Internacional application/pdf Universidad Nacional Autónoma de México Geofísica Internacional (México) Num.3 Vol.42